Primary appendiceal cancer with ovarian metastasis often presents with vague and nonspecific abdominal symptoms, and usually mimics advanced-stage ovarian primary malignancy. Because of the rarity of this disease and limited information provided by preoperative imaging, it is difficult to confirm the diagnosis before the operation; therefore the case is often mistaken as primary gynecological tumor rather than metastatic ovarian tumor, or KT8.
Reported factors that account for misdiagnosis include lack of history of gastrointestinal symptoms, abdominal distention, elevated serum tumor marker such as CA 125 levels, and outside pathology reports in support of ovarian primary9. Oncological surgeons should keep in mind that primary appendiceal cancer is a possible origin source when the diagnosis of ovarian tumor cancer is confirmed.
The results of permanent IHC staining for CK are different for primary appendiceal cancer and primary ovarian cancer. In primary adenocarcinomas of the large intestine and appendix, it is uniformly stained positively for CK 20 and presents typically in a diffuse pattern. Although CK20 is also positive for 75% of primary ovarian mucinous carcinomas, the staining is commonly patchy. In contrast, primary ovarian epithelial tumors of all cell types are stained for more than 96% of cases and the cytoplasm are typically strongly marked10, 11. However, permanent result of IHC staining is usually confirmed after surgery. If the diagnosis of primary appendiceal cancer can be established intraoperatively, it would not only lead to a correct diagnosis and optimal surgery but also avoid any subsequent operation; otherwise, occult appendiceal metastases might occur in patients with primary epithelial ovarian cancer (5-10% in early stage) and are diagnosed only after microscopic examination of the appendix12, 13. Appendectomy should be part of staging surgery in patients with presumed ovarian cancer, especially in muscinous ovarian cancer. In these two cases, the appendix was generally normal excepted a 1cm nodule near the tip in case 1, and ruptured in case 2. However, we should keep in mind that sometimes appendiceal cancer may appear even the appendix is macroscopically normal.
Adnexal tumors are common among women of all ages and malignant ovarian tumors need to be recognized in order to expedite appropriate treatment. Survival from primary appendiceal cancer depends on extent of tumor, tumor location, and cell type. Because of the rarity of primary appendiceal cancer, issues regarding diagnosis, surgical management, and adjuvant chemotherapy are not well established, although aggressive resection and treatment should be offered to young patients with ovarian metastasis, as this generally confers a 5-year survival advantage of 20-30%12.
Managing a pelvic mass is one of the common problems for gynecologists; unfortunately, there is no reliable method to distinguish between benign and malignant ovarian tumors. Gynecologists as well as radiologists should consider carcinoma of the appendix in the differential diagnosis of pelvic mass. Both of our cases were presented with elevation of CEA levels preoperatively, but their studies of barium enema and colonoscopy were normal. This might be a clue for us to make the diagnosis of metastatic ovarian tumor from GI tract. Abnormal elevation of CEA level is less common in early stages of primary ovarian cancer. On the other hand, in patients with colorectal cancer, it is associated with all stages of the disease. Some reports suggest that ovarian metastasis from colorectal origin should be consider in any patient whose CA-125/CEA ration is less than 2514. In our cases, the CA-125/CEA ration were 0.6 and 5.3 respectively.
Recent studies reveal Human Epididymis Protein 4 (HE4) is superior to distinguish benign ovarian tumors from primary ovarian malignancies15. Whether HE4 can be used to identify the primary ovarian cancer from metastatic tumors might need further evaluation. We suggest that the CEA and HE4 tests should be offered to patients with suspected ovarian tumors to assist in making preliminary diagnosis before surgery, especially those with primary sites that are difficult to determine.
Since primary appendiceal adenocarcinoma is rare, these cases remind gynecological surgeons to be familiar with primary appendiceal tumors and to inspect the appendix when the initial exploration surgery is to be performed. The clinical picture can be misleading and the differential diagnoses of primary appendiceal cancer should be considered when preoperative workup is planned.